Posterior Cervical Fusion of Occiput-T3 for Unstable Complex Odontoid Fracture in an 80-Year-Old Male With C2-Sacrum Synostosis From Ankylosing Spondylitis: A Case Report

Ankylosing spondylitis (AS) is an autoimmune arthritic condition that presents with inflammation of the axial skeleton and oligoarthritis of the peripheral joints. While its pathophysiology is not fully understood, the condition can lead to kyphosis and spontaneous intervertebral synostosis of the spine. AS is managed through both non-operative and operative means, but fractures in patients with AS are more complicated in those with synostosis. We present a case of a patient who is a tribal elder and Salish language instructor, with kyphotic AS with synostosis of C2-sacrum, and mobility confined to occiput-C1 and C1-C2. The patient suffered a low-energy fall backward from bed and presented to the orthopedic clinic approximately a month after his injury complaining of torticollis and neck pain. He was diagnosed to have a dens fracture, a right C2 pars/facet fracture, and a right lateral mass fracture with C1-C2 stenosis and cervical myelopathy. After the failure of conservative management, the patient required a full occiput-T3 fusion due to the osteoporosis and fragile AS synostosis of the spine, to mitigate transitional zone stresses that can occur with a shorter fusion. The fusion was successful, and it minimized the pain, corrected the torticollis, and allowed the patient to resume his tribal roles.